Steel alloys for springs

ABSTRACT

Steel alloy compositions for springs complying with the following specification:  
     0.51-0.55% by weight of carbon  
     1.15-1.25% by weight of manganese  
     0.15-0.30% by weight of silicon  
     0.90-1.10% by weight of chromium  
     0.15-0.25% by weight of molybdenum  
     0.10-0.15% by weight of vanadium  
     0.015-0.060% by weight of aluminum  
     0.015-0.030% by weight of niobium  
     0.008-0.012% by weight of nitrogen  
     and the balance iron and incidental impurities.

BACKGROUND OF THE INVENTION

[0001] The invention relates to novel steel alloys useful in making various products including vehicle leaf springs. Steel leaf springs for trucks and other vehicles have been in reasonably satisfactory extensive use for many years. However, improvements in certain properties have been desired. According to the present invention steel alloys are provided from which leaf springs, such as parabolic taper leaf truck springs, having improved properties and characteristics may be produced.

BRIEF SUMMARY OF THE INVENTION

[0002] The steel alloys of the present invention can be used to make leaf springs for vehicles exhibiting improvements in respect to ride characteristics, durability, weight, cost, strength, robustness, fatigue life and stress level efficiency.

DETAILED DESCRIPTION OF THE INVENTION

[0003] The spring steel alloys of the present invention have compositions within the following specification in which the alloying elements are present in the indicated concentrations in percentage by weight. Minimum Maximum Carbon 0.51 0.55 Manganese 1.15 1.25 Silicon 0.15 0.30 Chromium 0.90 1.10 Molybdenum 0.15 0.25 Vanadium 0.10 0.15 Aluminum 0.015 0.060 Niobium 0.015 0.030 Nitrogen 0.008 0.012 Iron Remainder

[0004] The aluminum is present as a deoxidizer so that the alloys are aluminum killed. The presence of incidental impurities such as phosphorus, sulphur, copper and tin can be tolerated when held to a minimum.

[0005] A preferred composition for an alloy of the present invention is as follows in percents by weight. Carbon 0.53 Manganese 1.20 Silicon 0.22 Chromium 1.00 Molybdenum 0.20 Vanadium 0.12 Aluminum 0.037 Niobium 0.022 Nitrogen 0.0010 Iron Remainder

[0006] The steel alloys of the invention may be produced in known manner by incorporating the alloying elements in the molten bath or melt. Likewise, the molten compositions can be made on a batch or continuous basis, and cast and processed in known manner.

[0007] While this invention has been described with reference to a preferred embodiment, it will be understood that this description shall not be construed in a limiting sense. Rather, various changes and modifications can be made to the preferred embodiment without departing from the true spirit and scope of the invention, as defined by the following claims. Furthermore, it will be appreciated that any such changes and modifications would be recognized by those skilled in the art as an equivalent to one element or more of the following claims, and shall be covered by such claims to the fullest extent permitted by law. 

1. A steel alloy consisting of: 0.51-0.55% by weight of carbon 1.15-1.25% by weight of manganese 0.15-0.30% by weight of silicon 0.90-1.10% by weight of chromium 0.15-0.25% by weight of molybdenum 0.10-0.15% by weight of vanadium 0.015-0.060% by weight of aluminum 0.015-0.030% by weight of niobium 0.008-0.012% by weight of nitrogen and the balance iron and incidental impurities.
 2. A spring alloy consisting of: 0.53% by weight of carbon 1.20% by weight of manganese 0.22% by weight of silicon 1.00% by weight of chromium 0.20% by weight of molybdenum 0.12% by weight of vanadium 0.037% by weight of aluminum 0.022% by weight of niobium 0.0010% by weight of nitrogen and the balance iron and incidental impurities. 